A good read that turns fascinating when it discusses the Supreme Court case Buck v. Bell which dealt with eugenical involuntary sterilization.
The term white trash dates back not to the 1950s but to the 1820s. It arises not in Mississippi or Alabama, but in and around Baltimore, Maryland. And best guess is that it was invented not by whites, but by African Americans. As a term of abuse, white trash was used by blacksâ€”both free and enslavedâ€”to disparage local poor whites. Some of these poor whites would have been newly arrived Irish immigrants, others semiskilled workers drawn to Baltimore and Washington, D.C. in the postrevolutionary building boom, and others still may have been white servants, waged or indentured, working in the homes and estates of area elites. The term registered contempt and disgust, as it does today, and suggests sharp hostilities between social groups who were essentially competing for the same resourcesâ€”the same jobs, the same opportunities, and even the same marriage partners.
While white trash is likely to have originated in African American slang, it was middle-class and elite whites who found the term most compelling and useful and they who, ultimately, made it part of popular American speech.